1. Field of Technology
The present invention relates to a method of and an apparatus for mounting minute electric and/or electronic components on an electric circuit wiring board such as a printed circuit board.
2. Description of the Prior Art
When minute leadless electric components such as exemplified by chip capacitors and chip resistors are to be mounted on a printed circuit board, it has long been practiced to apply a bonding agent to specific portions of the printed circuit board and then to successively supply the electric components onto the printed circuit board so that they can be bonded to the specific portions of the printed circuit board. The printed circuit board having the electric components mounted thereon is subsequently provided with external wirings for electrical connection by the use of a soldering technique.
A component mounting apparatus capable of performing the above described method has been proposed, which comprises a component mounting head capable of undergoing an indexed rotation and including a plurality of suction nozzles each operable to receive and hold under suction one of the electric components, which have been successively supplied at a component receiving station, and then to transport it to a component mounting station for the mounting onto the printed circuit board.
The component mounting apparatus of the type referred to above is schematically illustrated in FIGS. 23 to 26, reference to which will now be made for the detailed discussion thereof. In FIG. 23, reference numeral 300 designates the path along which each suction nozzle 312 (FIG. 25) undergoes a circular movement. Positions at which the suction nozzle 312 is brought to a halt include, with an exception, a component receiving station, a small component rectifying station, a big component rectifying station, a component inspecting station, a component mounting station, and a defective component rejecting station. At each of the big and small component rectifying stations, there is disposed a turntable 313, as shown in FIG. 25, where the centering of the electric component relative to the suction nozzle 312 and the adjustment of the angle of the electric component are carried out. More specifically, the turntable 313 has two pairs of rectifying fingers 314 and 315 mounted atop the turntable 313 for movement in a direction towards and away from each other, the direction of movement of the rectifying fingers 314 of one pair being perpendicular to that of the rectifying fingers 315 of the other pair. The electric component carried under suction by the suction nozzle 312 is rectified in position in two directions by the pairs of the rectifying fingers 314 and 315 while sandwiched between the rectifying fingers of the respective pair and the angle thereof is subsequently adjusted by causing the turntable 313 to be rotated by a drive belt 316. Change of the component mounting station at which the electric component is mounted on the printed circuit board is achieved by moving the printed circuit board.
While the mounting of the electric components is carried out in the manner as hereinabove described, it has been found difficult to cause the apparatus to have a checking function (hereinafter referred to as a verifier) for checking electric characteristics of each electric component, because the rectification of the position of the electric component and the angle adjustment of the same electric component are performed at one and the same station. This is because, as shown in FIG. 26, the suction nozzle 312 is fixed whereas the rectifying fingers undergo rotation while holding the electric component 8, and therefore, stable contact cannot be obtained between electrodes 317 of the electric component 8 and the adjacent rectifying fingers 314, making it impractical to provide an accurate characteristic checking. In order to stabilize the contact between the electrodes 317 and the adjacent rectifying fingers 314, a relatively long time is required, posing a problem in that the tact time in the production line tends to be prolonged.
Moreover, the verifier hitherto used is of a design wherein the electrodes are sandwiched from two directions while sucked onto the suction nozzle, and therefore, depending on the suction posture, an exact contact with the electrodes does not always take place.